1. Field of the Invention
The present invention relates to the field of liquid crystal displaying, and in particular to a liquid crystal display device and a manufacturing method thereof.
2. The Related Arts
A liquid crystal display device generally comprises a TFT (Thin-Film Transistor) substrate, a CF (Color Filter) substrate attached to the TFT substrate, and liquid crystal interposed between the TFT substrate and the CF substrate. Both the TFT substrate and CF substrate are covered with a transparent conductive film (ITO). Afterwards, an alignment film is attached to the two transparent conductive films. The alignment film functions to align liquid crystal molecules.
A general process for forming an alignment film is that an alignment solution is sprayed from a nozzle of a spraying head to the TFT substrate and the CF substrate. The alignment solution is then kept still for a while to allow the solution to spread out to form a film. Finally, baking is carried out to complete the formation of the alignment film. However, it is generally hard to control the amount of the alignment solution sprayed from the nozzle and this usually results in uneven thickness of the alignment film and consequently, the displaying characteristics of the product are affected. In addition, being kept still is necessary in the known process requires for the alignment solution to spread out and this lowers down the manufacture efficiency.
To overcome such a problem, a known technique uses printing or ink-jetting process to coat an alignment film (generally made of polyimide, PI) on the TFT substrate and CF substrate, followed by baking and rubbing operations to complete the alignment process. Further, in MVA (Multi-Domain Vertical Alignment) techniques, bumps of specific shapes or fish-bone like ITO must be formed, or a polymerizable monomer is added in the liquid crystal to allow alignment to be accomplished through ultraviolet polymerization by applying an electrical voltage.
However, these known processes of alignment are subjected to undesired constraints in controlling the size and marginal configuration of an alignment film.